I had two of the first generation Nest Hello doorbells hooked up to a single chime, using the wiring diagram in this thread:
I recently upgraded to the new Nest Doorbell wired 2nd generation and attempted to use the Nest chime included, but it would not work as shown in this diagram:
Ultimately it would not work with the new chime connectors, so I reverted back to the old wiring diagram with original chime connectors (just hooking up the new 2nd gen doorbells) and it worked.
Well, after a couple of weeks I noticed that both doorbells are offline and do not appear to be getting power. I flipped the 120v breaker and it did not help. No lights at all on the doorbells, or ringing when the doorbell is pressed. I notice that the transformer requirement states the new version requires a 16-24 V AC, 10-40 VA transformer. What is the transformer requirement for running two of the 2nd generation wired doorbells off of a single chime? Does anyone have any clue why they would suddenly stop working, apparently both at the same time?
I had a brief exchange with my electrician and determined that not only was my old transformer putting out enough power for two of the new nest doorbells, but that my old transformer also had stopped working. I went to Home Depot and picked up a new transformer, and wired up the new chime connects. At first, only one of the doorbells would actually ring the chime. However, after waiting a few minutes, both started working. I guess when you are using two of the chime connectors you have to be patient before both chimes will ring. Issue has been resolved!